From 98cadd4b9fa8e32d1d0dea8e46b5ba829af4e8a2 Mon Sep 17 00:00:00 2001
From: Alexey Neyman <stilor@att.net>
Date: Wed, 8 Feb 2017 16:00:57 -0200
Subject: [PATCH] sh: Fix building with gcc5/6

Build glibc for sh4-unknown-linux-gnu currently fails if one's
using GCC5/6: in dl-conflict.c, the elf_machine_rela() function
is called with NULL as its 3rd argument, sym. The implementation
of that function in sysdeps/sh/dl-machine.h dereferences that pointer:

const Elf32_Sym *const refsym = sym;
...
if (map == &GL(dl_rtld_map))
  value -= map->l_addr + refsym->st_value + reloc->r_addend;

GCC discovers a null pointer dereference, and in accordance with
-fdelete-null-pointer-checks (which is enabled in -O2) replaces this
code with a trap - which, as SH does not implement a trap pattern in
GCC, evaluates to an abort() call. This abort() call pulls many more
objects from libc_nonshared.a, eventually resulting in link failure
due to multiple definitions for a number of symbols.

As far as I see, the conditional before this code is always false in
rtld: _dl_resolve_conflicts() is called with main_map as the first
argument, not GL(_dl_rtld_map), but since that call is in yet another
compilation unit, GCC does not know about it. Patch that wraps this
conditional into !defined RESOLVE_CONFLICT_FIND_MAP attached.

	* sysdeps/sh/dl-machine.h (elf_machine_rela): The condition
	in R_SH_DIR32 case is always false when inlined from
	dl-conflict.c. Ifdef out to prevent GCC from insertin an
	abort() call.

[Waldemar: backport of
https://sourceware.org/git/?p=glibc.git;a=commit;h=d40dbe722f004f999b589de776f7e57e564dda01.]
Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
---
 sysdeps/sh/dl-machine.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/sh/dl-machine.h b/sysdeps/sh/dl-machine.h
index 5bb37d0..6509055 100644
--- a/sysdeps/sh/dl-machine.h
+++ b/sysdeps/sh/dl-machine.h
@@ -389,7 +389,7 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 	  break;
 	case R_SH_DIR32:
 	  {
-#ifndef RTLD_BOOTSTRAP
+#if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
 	   /* This is defined in rtld.c, but nowhere in the static
 	      libc.a; make the reference weak so static programs can
 	      still link.  This declaration cannot be done when
-- 
2.7.4

